importing chrome extension

clients/chrome/background.ts

@@ -0,0 +1,92 @@
+// A list of: {
+//   id: number;
+//   path: string;
+// } where [id] is the [connectionId] (internal to Chrome) and [path] is the
+// OS' name for the device (e.g. "COM4").
+interface Connection {
+  id: string;
+  path: string;
+}
+let connections: Connection[] = [];
+
+// A list of "ports", i.e. connected clients (such as web pages). Multiple web
+// pages can connect to our service: they all receive the same data.
+let ports = [];
+
+interface Message {
+  type: string;
+  data: string;
+  id: string;
+}
+
+function byPath(path: string): Connection[] {
+  return connections.filter((x) => x.path == path);
+}
+
+function byId(id: string): Connection[] {
+  return connections.filter((x) => x.id == id);
+}
+
+function onReceive(data, id: string) {
+  if (ports.length == 0) return;
+
+  let view = new DataView(data);
+  let decoder = new TextDecoder("utf-8");
+  let decodedString = decoder.decode(view);
+  ports.forEach(port => port.postMessage(<Message>{
+    type: "serial",
+    data: decodedString,
+    id: id,
+  }));
+}
+
+function findNewDevices() {
+  chrome.serial.getDevices(function (serialPorts) {
+    serialPorts.forEach(function (serialPort) {
+      if (byPath(serialPort.path).length == 0 &&
+        serialPort.displayName == "mbed Serial Port") {
+        chrome.serial.connect(serialPort.path, { bitrate: 115200 }, function (info) {
+          // In case the [connect] operation takes more than five seconds...
+          if (info && byPath(serialPort.path).length == 0)
+            connections.push({
+              id: info.connectionId,
+              path: serialPort.path
+            });
+        });
+      }
+    });
+  });
+}
+
+function main() {
+  // Register new clients in the [ports] global variable.
+  chrome.runtime.onConnectExternal.addListener(function (port) {
+    if (/^(micro:bit|touchdevelop|yelm|pxt|codemicrobit|codethemicrobit)$/.test(port.name)) {
+      ports.push(port);
+      port.onDisconnect.addListener(function () {
+        ports = ports.filter(function (x) { return x != port });
+      });
+    }
+  });
+
+  // When receiving data for one of the connections that we're tracking, forward
+  // it to all connected clients.
+  chrome.serial.onReceive.addListener(function (info) {
+    if (byId(info.connectionId).length > 0)
+      onReceive(info.data, info.connectionId);
+  });
+
+  // When it looks like we've been disconnected, drop the corresponding
+  // connection object from the [connections] global variable.
+  chrome.serial.onReceiveError.addListener(function (info) {
+    if (info.error == "system_error" || info.error == "disconnected" || info.error == "device_lost")
+      connections = connections.filter((x) => x.id != info.connectionId);
+  });
+
+  // Probe serial connections at regular intervals. In case we find an mbed port
+  // we haven't yet connected to, connect to it.
+  setInterval(findNewDevices, 5000);
+  findNewDevices();
+}
+
+document.addEventListener("DOMContentLoaded", main);